Greywater treatment in an aerobic SBR: sludge structure and kinetics.

In order to have an efficient operation, sequencing batch reactors (SBR) must support granular biomass with high conversion rates, settling properties, and be able to deal with the inherent variability of the composition of real wastewaters. In this study, the effect of the influent composition and the specific organic loading rate (Bx) on the granulation process was evaluated in two SBRs, fed with greywater (GW) and a synthetic medium (SM). The feeding with SM led to the formation of compact granular biomass, with a sludge volume index (SVI) of 22.4 mL g-1, and a zone settling velocity (ZSV) of 13.1 m h-1. In contrast, feeding with GW induced the formation of filamentous granules, with lower settling properties (SVI = 165 mL g-1 and ZSV = 10 m h-1), when the system was operated at high Bx (4.4 kg COD kg VSS-1 d-1). However, the reduction of the average Bx to 2 kg COD kg VSS-1 d-1 induced an improvement in the morphology and properties of the granules (SVI = 98 mL g-1 and ZSV = 13 m h-1). Furthermore, the kinetic analysis indicated that granules cultivated with SM were formed by fast growing microorganisms with a high cell yield, whereas those cultivated in GW presented a much lower cell yield.

TRPA1 Channels Mediate Human Gingival Fibroblast Response to Phenytoin.

Drug-induced gingival enlargement (GE) is a frequent adverse effect observed in patients treated with anticonvulsant, immunosuppressant, and some antihypertensive medications-the antiepileptic phenytoin being the main drug associated with GE due to its high incidence (around 50%). The molecular mechanisms behind drug-induced gingival overgrowth are still unknown. By reverse transcription polymerase chain reaction, we demonstrate that the calcium-permeable ion channels TRPA1, TRPV1, and its capsaicin-insensitive isoform TRPV1b are expressed in human gingival fibroblasts (HGFs), the most abundant cellular type in periodontal tissue. Cultured HGFs responded with intracellular calcium elevations to phenytoin and to the canonical TRPA1 agonist allyl isothiocyanate. Application of phenytoin activated a nonselective cationic current in HGFs with a typical signature for TRPA1 channels. Moreover, this activation was blocked by HC030031, a specific TRPA1 blocker. Similarly, the use of shRNAs against hTRPA1 in HGFs reduced TRPA1 expression and activation by phenytoin. In addition, we show that phenytoin increased intracellular calcium levels in cells transfected with mouse or human TRPA1 channels. Responses to phenytoin were not observed in untransfected cells or cells expressing TRPM8 or TRPV1. The activation of HGFs by phenytoin was markedly reduced in the presence of antioxidant vitamins: ascorbic acid, folic acid, and α-tocopherol. By performing cell proliferation assays, we found that phenytoin did not augment the proliferation rate of HGFs. In contrast, alcian blue and picrosirius red staining of long-term HGFs cultures indicated that phenytoin induces extracellular matrix accumulation of collagen. Collectively, these findings support an important role of TRPA1 channels in phenytoin-induced GE, provide insight into the pathophysiologic mechanism, and offer novel therapeutic opportunities for its treatment.

Electrotunable lubricity with ionic liquid nanoscale films.

One of the main challenges in tribology is finding the way for an in situ control of friction without changing the lubricant. One of the ways for such control is via the application of electric fields. In this respect a promising new class of lubricants is ionic liquids, which are solvent-free electrolytes, and their properties should be most strongly affected by applied voltage. Based on a minimal physical model, our study elucidates the connection between the voltage effect on the structure of the ionic liquid layers and their lubricating properties. It reveals two mechanisms of variation of the friction force with the surface charge density, consistent with recent AFM measurements, namely via the (i) charge effect on normal and in-plane ordering in the film and (ii) swapping between anion and cation layers at the surfaces. We formulate conditions that would warrant low friction coefficients and prevent wear by resisting "squeezing-out" of the liquid under compression. These results give a background for controllable variation of friction.

Electrotunable Friction with Ionic Liquid Lubricants: How Important Is the Molecular Structure of the Ions?

Using nonequilibrium molecular dynamics simulations and a coarse-grained model of ionic liquids, we have investigated the impact that the shape and the intramolecular charge distribution of the ions have on the electrotunable friction with ionic liquid nanoscale films. We show that the electric field induces significant structural changes in the film, leading to dramatic modifications of the friction force. Comparison of the present work with previous studies using different models of ionic liquids indicate that the phenomenology presented here applies to a wide range of ionic liquids. In particular, the electric-field-induced shift of the slippage plane from the solid-liquid interface to the interior of the film and the nonmonotonic variation of the friction force are common features of ionic lubricants under strong confinement. We also demonstrate that the molecular structure of the ions plays an important role in determining the electrostriction and electroswelling of the confined film, hence showing the importance of ion-specific effects in electrotunable friction.

Friction through reversible jumps of surface atoms.

We propose a microscopic model that incorporates the effect of thermally activated motion of surface atoms on nanoscopic friction. Our calculations demonstrate that the stick-slip motion of the tip is governed by two competing processes: (i) jumps of the surface atoms to the tip which tend to inhibit sliding, and (ii) jumps back to the sample which give rise to sliding. The energy dissipated during the reversible jumps of the surface atoms between the sample and tip contributes significantly to the friction force, and leads to a nonmonotonic dependence of friction on temperature, which has been observed in recent friction force microscopy experiments for different material classes. The proposed model elucidates the physical origin of microscopic instabilities introduced in phenomenological models for the interpretation of the experimental results.

Thermal activation at moderate-to-high and high damping: finite barrier effects and force spectroscopy.

We study the thermal escape problem in the moderate-to-high and high damping regime of a system with a parabolic barrier. We present a formula that matches our numerical results accounting for finite barrier effects, and compare it with previous works. We also show results for the full damping range. We quantitatively study some aspects on the relation between mean first passage time and the definition of an escape rate. To finish, we apply our results and considerations in the framework of force spectroscopy problems. We study the differences on the predictions using the different theories and discuss the role of γF[over dot] as the relevant parameter at high damping.

Surface defects and temperature on atomic friction.

We present a theoretical study of the effect of surface defects on atomic friction in the stick-slip dynamical regime of a minimalistic model. We focus on how the presence of defects and temperature change the average properties of the system. We have identified two main mechanisms which modify the mean friction force of the system when defects are considered. As expected, defects change the potential profile locally and thus affect the friction force. But the presence of defects also changes the probability distribution function of the tip slip length and thus the mean friction force. We corroborated both effects for different values of temperature, external load, dragging velocity and damping. We also show a comparison of the effects of surface defects and surface disorder on the dynamics of the system.

Mithramycin reduces expression of fibro-proliferative mRNAs in human gingival fibroblasts.

Fibrosis is characterized by loss of normal structure and function of a tissue or organ resulting from excessive fibroblast proliferation and extracellular matrix production. Currently, there is no efficient treatment for fibrosis. Herein, we test effects of the drug mithramycin, which targets the Sp1 family of transcription factors, on mRNA expression by human gingival fibroblasts. Mithramycin reduced expression of connective tissue growth factor and type I collagen mRNAs. Microarray profiling revealed that mithramycin selectively blocked expression of cell proliferation and transforming growth factor-beta (TGF-ß) signalling clusters. These microarray data were validated using real-time polymerase chain reaction and western blot analyses. Mithramycin suppressed expression of key profibrotic TGF-ß signalling mediators, Smad3 and p300, as well as cell proliferation. Taken together, these data suggest that the Sp1 family of transcription factors may contribute to expression of fibrogenic genes in human gingival fibroblasts; drugs targeting the Sp1 family may be beneficial in treatment of fibro-proliferative diseases.

Serotonin, serotonin 5-HT(1A) receptors and dopamine in blood peripheral lymphocytes of major depression patients.

There are increasing evidences of cell markers present in the immune and the nervous systems. These include neurotransmitter receptors and transporters. Serotonin receptor subtypes are related to depression and also have been shown to be present in certain cells of the immune system. In the present report, we determined the presence of 5-HT(1A) receptors by the binding of the selective agonist 8-hydroxy-2-(di-n-propyl-amino)tetralin in lymphocytes of peripheral blood isolated by Ficoll/Hypaque gradients from controls and depressed patients. The capacity of these receptors was around 24 fmol/10(6) cells in both groups of subjects, without significant difference among them. The affinity was in the nM range and either differ between controls and patients. Serotonin, 5-hydroxyindoleacetic acid, dopamine and 3,4-dihydroxyphenylacetic acid were determined by HPLC with electrochemical detector. There were no significant differences between controls and major depression patients in the values obtained for rich and poor platelet plasma or in the isolated cells. However, there was a reduction in serotonin turnover rate indicated by an increase in the ratio serotonin/5-hydroxyindoleacetic acid, but not in that of dopamine, in lymphocytes of major depression patients. Thus, there is a serotonergic dysfunction in immune circulating cells of major depression patients, without changes in the number of 5-HT(1A) receptors, although the coupling of these receptors to transduction mechanisms could be affected and may be related to the alteration of 5-HT turnover rate.

Effects of sodium arsenite exposure on development and behavior in the rat.

Arsenic is an environmental contaminant found in soil, water and air in some zones of the world. It has been widely studied for its effects as a human carcinogenic agent, but few studies have dealt with neurobehavioral effects. In addition, studies of arsenic effects on development have only addressed its effects on embryotoxicity and teratogenicity after a single oral, gavage or intraperitoneal exposure. Among the behavioral alterations reported after intoxication with arsenic are both increased and decreased locomotor activity and learning deficits in a delayed alternation task [Toxicol. Lett. 54 (1990) 345; Bull. Environ. Contam. Toxicol. 50 (1993) 100; Brain Res. Bull. 55 (2001) 301]. To further characterize developmental and behavioral alterations induced by arsenic exposure, Sprague-Dawley rats were exposed to arsenite (36.70 mg arsenic/l in drinking water) from gestation day 15 (GD 15) or postnatal day 1 (PND 1), until approximately 4 months old. The pregnant or lactating dams received either the arsenic solution or regular drinking water and once pups were weaned, they continued receiving the same solution as drinking water. Animals exposed from GD 15 showed increased spontaneous locomotor activity and both exposed groups showed increased number of errors in a delayed alternation task in comparison to the control group. Total arsenic (TA) content in brain was similar for both exposed groups and significantly different from the control group. These results indicate that rats exposed to arsenic during development present deficits in spontaneous locomotor activity and alterations in a spatial learning task.

Folate receptors targeted to clathrin-coated pits cannot regulate vitamin uptake.

Potocytosis is an endocytic process that is specialized for the internalization of small molecules. Recent studies on the uptake of 5-methyltetrahydrofolate by the folate receptor have suggested that the glycosyl-phosphatidylinositol anchor on this protein causes it to cluster and be internalized by caveolae instead of coated pits. To test this hypothesis directly, we have constructed a chimeric folate receptor that has the glycosyl-phosphatidylinositol anchor replaced with the transmembrane domain and cytoplasmic tail of the low density lipoprotein receptor. The cells with wild-type receptors delivered 5-methyltetrahydrofolate to the cytoplasm more rapidly than did cells expressing the chimeric receptor. This suggests that efficient delivery to the cytoplasm depends on caveolae. In sharp contrast to cells with wild-type folate receptors, cells internalizing folate by clathrin-coated pits were unable to decrease vitamin uptake when they were either folate replete or confluent.

The polymorphic expression of lactase in adults is regulated at the messenger RNA level.

BACKGROUND/AIMS: Lactase phlorizin hydrolase (LPH) activity is high in infants but declines 80%-90% before adulthood in most mammals, including humans. However, 95% of whites show autosomal dominant inheritance of a lifelong high lactose digesting capacity (LDC). This study attempted to clarify the molecular mechanism(s) of this phenomenon (posttranslational vs. pretranslational). METHODS: A race- and sex-balanced cohort (n = 20) was studied, and lactose tolerance and levels of jejunal lactase protein, activity, and messenger RNA (mRNA) were measured. RESULTS: These data confirm that black heritage predicts low LDC, and white heritage predicts high LDC. Lactase breath hydrogen and determination of lactase/sucrase ratio (L/S) from jejunal biopsy specimens divide the group by high and low LDC phenotypes concordantly. All subjects with an L/S ratio > 0.5 had immunodetectable LPH protein and measurably higher LPH mRNA levels than the remaining subjects. LPH mRNA levels are highly correlated with lactase specific activity (r = 0.80) and L/S ratio (r = 0.88). CONCLUSIONS: The direct correlation between LPH mRNA levels and lactase expression argues that the gene responsible for the human lactase polymorphism regulates the level of LPH mRNA.

Biologia de Anopheles (Kerteszia) neivai H., D. & K., 1913 (Diptera: Culicidae) en la costa Pacífica de Colombia. I - Fluctuación de la población larval y caracteristicas de sus criaderos / Biology of Anopheles (Kerteszia) neivai, H., D. & K., 1913 (Diptera: Culicidae) on the Pacific Coast of Colombia. I - Fluctuation of larval population and characteristics of the breeding places

En Charambirá, localidad del município de Istmina (Chocó) en la costa Pacífica de Colombia, donde existe un problema de malaria endêmica, se estudió la fluctuación de la población larval y las características de los criaderos de Anopheles (Kerteszia) neivai, especie considerada como posible vectora de malaria en esa región del país. La vegetación circundante fué dividida en tres estratos de acuerdo al grado de cobertura foliar. Se demarcaron cuadrantes de 100 m2 en cada estrato para el muestreo de plantas epíftas de la família Bromeliaceae, en las cuales se acumula agua que sirve como criadero para esta especie de anofelino. Se tomaron datos de temperatura, pH y volumen del agua contenida en cada bromelia. El mayor número de larvas se detectó en el estrato 1 (manglar) a una altitud inferior a 4 m, pero no se encontró evidencia significativa de estratificación vertical de la apoblación larval de A. neivai hasta los 8 m. Se evidenció una correlación lineal positiva entre el número de larvas y el volumen de agua contenida en cada bromelia; por otra parte se observó también una correlación directa entre la precipitación mensual acumulada y la fluctuación poblacional de esta especie. Los índices larvales mas altos se observaron entre los meses de marzo a abril y de julio a agosto. La mortalidad larval fué alta en el primer estadio (43,5

Biologia de Anopheles (Kerteszia) neivai H., D. & K., 1913 (Diptera: Culicidae) en la costa Pacífica de Colombia. II. Fluctuación de la población adulta / Biology of Anopheles (Kerteszia) neivai H., D. & K., 1913 (Diptera: Culicidae) on the Pacific Coast of Colombia. II. Adult population fluctuation

En la localidad de Charambirá, situada en el município de Istmina (Chocó) en la costa Pacífica de Colombia, se presenta un problema de malaria endêmica asociada con grandes poblaciones de mosquitos Anopheles del subgénero Kerteszia (A. neivai). Estos se crían en las colecciones de agua formadas por plantas epífitas de la família Bromeliaceae, que son muy abundantes en los árboles de mangle. En esa localidad se estudiaron: fluctuación poblacional y algunos aspectos ecológicos y etológicos de los adultos de esa especie de mosquito, con el objetivo de determinar su papel en la tranmisiòn de malaria. Todos los mosquitos fueron colectados por cebos humanos. Los picos máximo de actividad ocurrieron en las horas crepusculares de la mañana y de la tarde (5:30 a 6:30 y 18:00 a 19:00 horas). En el período nocturno la actividad intradomiciliar fué baja y no hubo ninguna durante el día. El estado gonadotrófico de las hembras colectadas durante nos picos de actividad, mostró la existencia de dos poblaciones de mosquitos: una, en su mayoría individuos jóvenes que buscam su alimento en las horas de la tarde y la otra compuesta por individuos mas longevos, que buscam su alimento en la mañana. El estudio de la variación estacional mostró que las poblaciones son bajas en los meses de poca precipitación, pero a medida que aumenta el índice pluviométrico, aumenta el número de mosquitos. Se discute la relación que existe entre la presencia de los mosquitos y la prevalencia de malaria humana; se sugiere que A. neivai puede ser el responsable de la transmisión de malaria en la zona estudiada.

Biologia de Anopheles (Kerteszia) neivai H., D. & K., 1913 (Diptera: Culicidae) en la costa Pacífica de Colombia. III - Medidas de luminosidad y el comportamiento de picadura / Biology de Anopheles (Kerteszia) neivai H., D. & K., 1913 (Diptera: Culicidae) on the Pacific Coast of Colombia. III - Ligth intensity measurements and biting behavior

El estudio del comportamiento de picadura de mosquitos capturados picando humanos en un área despejada del poblado de Charambirá, Chocó, en la costa Pacífica de Colombia, indicó que cambios en la intensidad de la luz, influenciaban el início y el fin de la actividad de vuelo de Anopheles (Kertszia) neivai, especie con marcados hábitos crepusculares. Esta especie está considerada como vectora de esa enfermedad, malaria, en la costa pacífica colombiana.